单选题 The dynamics of population of the algae (藻类) that resulted in red tide (赤潮) belongs to ( ).

单选题 Whale, dolphin, sea lion, sea elephant, and sea dog all belong to mammal, and shark belongs to fish, but they all have the fin-like structure to adapt themselves to water environment. We can term this phenomenon ( ).

单选题 The basic unit of species’ existence in nature is ( ).

单选题 The auricle (外耳) of arctic fox (北极狐) is markedly shorter than that of red fox (赤狐) in temperate zone, and the auricle of red fox is obviously shorter than that of large-ear fox (大耳狐). We can use ( ) to explain this phenomenon.

单选题 The proportion of quantity of nitrogen (氮), potassium (钾), phosphorus (磷) that a crop needs to grow and develop normally (正常生长发育) is 5 : 7: 10, and which of them is 2: 4: 5 in the soil where this crop inhabits (栖息, 存在于). According to the background (背景) above, we can infer (推断) that ( ) is the limiting factor (限制因子) for this crop in the soil.

单选题 For the fish in a tank (水族箱), ( ) most probably becomes the limiting factor.

单选题 The position of light compensation point (光补偿点) for sun species (阳地或阳性物种) is ( ) that for shade species (阴性或阴地物种).

单选题 When there are short of calcium (钙) in the environment, strontium (锶) can substitutes for calcium (Ca.) in the growth and development of mollusk. We can term this effect as ( ).

单选题 A secondary metabolized material (次生代谢产物) is released into environment by a plant, which can inhibited the other plants from growth, we often term this phenomenon as ( ).